Apparatus for finishing high-grade gears



May 31 1927.

v 'w. E. HOKE APPARATUS FOR FINISHING HIGH GRADE GEARS 4 Sheets-Sheet 1 Filed Jan. 11. 1924 May: 31 w. 5.14am:

- APPARATUS m smsm u'e awn saws cums med Jan. 11, 1924 4 Sheets-She et 2 May 31 1927.

w E. HOKE APPARATUS FOR FINISHING HIGH GRADE GEARS Filed Jan. 11, 1924 4 Sheets-Sheet 3 abtozmugo.

M 1927' E. H'O K E,

Arrmurugron Fmsnrwnmn GRADE GEARS Filed Jan. 11. 1924 4 Sheptg-Sheet 4 Patented May 31, 1927.

UNITED STATES WILLIAM E. HOKE, OF BALTIMORE, MARYLAND..

APPARATUS FOR FINISHING HIGH-GRADE GEARS.

This invention relates to a method of and apparatus for accuratelyfinishing gears.

In the manufacture of gears, particularly those used in automobile transmission, it has 6 heretofore been the practice to machine and harden the gears and in addition to subject them to a finishing process termed, wearing them in. The purpose of this process is to eliminate roughness, which would result in noisy operation.

In some instances gears to be finished or worn in are merel put in mesh and subjected, a suitable a rasive being applied, to an adjustable load.' In other instances a 1 gear to be finished is lapped by being meshed with a gear'of softer material, such as cast iron. This latter method is based on the theory that the abrasive used in all cases embeds itself in the softer metal and wears away the harder metal.

It. also has been proposed to systematically wear in gears by causing two gears to be finished to wear against each other and thereby mutually correct each other.

95 However.; also these methods rely on a more or less fortuitous wearing action.

It is a general object of this invention to provide a method of and an apparatus for WEiil'lIlg in and truing gears, and producing gears having teeth concentric, equally spaced, and with conjugate surfaces.

Another object is to provide an apparatus by means of which the wearing-in operation may be performed in less time than has heretofore been possible.

Briefly stated, the inventionv in its broader aspect consists in making a gear or gears to be worn in a part of a closed gear train, then adjusting the elements of the gear train relatively to each other in any of many ways suitable or by any of many means available for taking out the back lash and establishing, at will, any desired pressure reaction of the gears upon each other then subjecting the gear to be worn in to a continued abrasive action, which may be produced by causing an abrasive to act upon the gear, as for'instance, through the agency of a lapping gear Application filed January 11, 1824 Serial No. 886,686.

forming likewise a member of the train,

while operating the train, and gradually adjusting the pressure reaction between the gears to maintain a desired wearing load until the operation is com leted.

The invention and t e principle of operation upon which it is based may be full understood from the specification of whic the acoom ianying drawings are a part.

In the rawings:

Fig. 1 is a plan view of an arrangement embodying the invention;

F g. 2 'is an elevation thereof; v

Fig. 3 is a plan View of an arrangement :howmg another application ofth'e invenion;

Figs. 4 and 5 are a plan view and a side view diagrammatically representing'another modification v Fig. 6 is a diagrammatic plan view explaining the principles of operation;

Figs. 7 and 8 are a plan View and a section respectively of another modification;

Fig. 9 1s a more or less diagrammatic View showing another mode of applying the principles of the invention; an

F ig. 10 is..a more or less diagrammatic view showing a modification thereof.

Assume that the gears 10, 11, 12 and 13 in F 1g. 1 are gears to beworn in and trued, I use a toggle link system in which the links 14, 15, 16 and 17 are pivotally interconnected by the shafts 18 of the gears. The

different links have each a length from pivot to pivot corres ionding substantially tothe' distance from t 1e center of one gear to the center of another gear fully in mesh with it. as V For the sake of mechanical rigidity I prefer to use between the same studs a plurality of links in spaced relation as indicated in Fig. 2.

\Vhen the ears are mounted on their reso spective shaits, they form an interlinked gear train one ear train closed upon itself. When the togge link is in what may be called a neutral osition, each ar has a certain amount 0 play, common y referred as to as backlashf? relatively to the adjacent gears and the whole train has a certain like Si amount of play. When pressure is applied to the link system inwardly from opposite corners, this backlash is taken up, which means that all teeth of the gear train that may at any time be in mesh, arein definite forced contact relation whether the gear train operates in one direction or in the opposite direction, in the sense that like sides of all the teeth of any one of two matin gears are successivel engaged by des of the teeth of the 'ot er gear, while the remaining sides of the teeth of the same two gears are not in wearing contact with each other. When pressure is applied from .the other opposite corners of the link system, the pla is likewise taken up, but the relativity of forced contact points is ,reversed, which means that contact between the successively interacting teeth of any two gears takes place on that side \of each tooth I which was previously out of wearing contact.

When, after pressure was applied in one diagonal, pressure is applied in the other d1- agonal, contact between the teeth of two gears is thrown from one side to the other side of the teeth.

The significance of this feature is as follows:

Since there is always a certain amount of lay between gears, the teeth of two gears 1n mesh with each other will normally accommodate themselves according to conditions.. Assume that the teeth of a pair of meshing gears are imperfectly spaced or have some other imperfection which must be worn off in order to obtain a silent gear. During the usual wearing-in operations as soon as the imperfection on one gear comes into contact with a tooth on the other fiear, a slight relative angular movement w take place between the two gears tending to take up the play. In other words, the driven gear yields to the driving gear.

With the arrangement described, the playcan be initially taken up and any unevenness or rough spot is subjected not merely to the wearing action of a force corresponding to the load carried but also to the grinding action of the op osing teeth which follow rigidly a prescribed path. When the rough spot assumed comes into contact with a. tooth on the opposing gear, neither of the gears can yield forwar ly or rearwardly as the case ma be, because there is no play. If the mes ing teeth happen to be of correct form, there is, of course, no lapping action, because there is no pressure exerted. It will be understood that a suitable abrasive is used to cause the necessary grinding action.

Many gears run noiselessly at light load but become noisy under heavy-load. This is attributed to the bending of the teeth under dubbin teeth load which causes the points of the adjacent teeth to strike when they in turn come into contact. In order to avoid this, many manufacturers make teeth of a modified involute curvature, the modification consisting in a 011' slightly the ends so that the 0 not strike but come into contact gradually with a sliding movement, as they should. This modification has been entirely empirical heretofore. By the arrangement proposed the dubbing olf is done naturally and effectively by the arrangement described by controlling the load conditions.

The pressure or load may be applied as indicated or in any other equivalent manner. At diametrically opposite points of the link system the shafts carrying the gears may be connected to bars 19 and 20 having bearings for the shafts. One of the bars may be held stationary by any suitable means while the other shaft may be movably su ported. As indicated, pressure may be appiied in opposite directions by turning nuts 21 and 22 on the screw-threaded shank of bar '23 against an abutment 24. When the nut 22 is loosened and the nut 21 turned up against the abutment 24, the pressure is applied inwardly. When the nut 21 is loosened and' time to time the intercenter distance and thereby the amount of overla In the drawing the mode oi applying pressure is merely intended forthe purpose of illustration. In practice mechanism may be provided for quickl changing the direction of theapplication 0 pressure, as for instance a lever arrangement similar to gear shift levers, coupling operating levers or clutch opera-ting levers, whereby the pressure ma not only be quickly varied but also reverse The gears represented in Figs. 1 and 2 have 54, As is well understood, in case two gears have the same number of teeth the same teeth will always come into contact with each other. In cases where they have a different number of teeth, the same teeth will come into mesh The length of the links may be made adjustable for the purpose of varying from' v 50, 45 and 40 teeth respectively.

a ain only after two or more revolutions.

or instance, as to the two gears having 45.

and 40 teeth respectively, after eight revolu-' tions of the former and nine revolutions of the latter the same teeth come again into con-. I

it is a simple matter to-change the ositiom- Gears, the number of teeth of which have no common factor-and whose teeth differ only by a small number, need not be turned as often as other gears. Gears which run on the huntin stance a gear having 49 teeth and another 50 teeth, need of course, not be angularly ,turned at 'all. It is merely emphasized that where turning is desirable, it may be readily and quickly accomplished... J

The more completely'llie interengagement of the teeth is varied, i. e. the'more difi'erent teeth are brought into mesh with each other, the more uniform will be the teeth after the operation.

The mode of operation described applies, of course, also to compound gearing, for 1nstance a shaft carrying a gear and a pinion, it being merely necessary to suitably modify the link arrangement and make such other minor changes as may be found desirable for the purposes of the invention. It applies to gears of all. kinds, viz: bevel gears, spur gears, spiral gears, herringbone-gears, etc.

' Fi .3 shows an application of the invention I01 wearing in bevel gears. In the particular example is disclosed a typical ,arrangement including two bevel bears and 26 and two pinions 27 and 28 forming a gear train closed upon itself. The shafts 29 and 30 of the pinions are mounted in yoke links 31 and 32 which are pivotally interconnected through the shafts 33 and 34 of thegears 25 and 26, respectively, as pivots. When pressure is applied to move one of the yokes, while the other is held stationary, motion of the link which is moved takes place about the axes of the gears 25 and 26I" The links might of course b pivoted in the shafts of the pinions and connected to the shafts of the gears. The effect is the same in one case as in the other. It is merely necessary that the gears are relativelymovable one about the axis of another in mesh with it and that the intercenter distance is maintained constant.

Figs. 4 and 5 show an application of the invention-for wearing in compound gears. The compound gears comprising a gear 35 anda pinion 36 on shaft 37, on t e one hand,

- and a gear 38 and a pinion 39'mounted on a shaft 40 0n the other hand, are in mesh with lapping gears 41 and 42 respectively to con stitute a gear train closed upon itself. The

shafts 37 and 40 may be suitably interconnected with the shafts 43 and 44 of the lapping gears by a link connection similar to that shown in Figs. 1 and 2. To avoid com-j -plication of the drawing this link mechanism is not shown, the relative movement of the, shafts bein indicated by the arrows. It is understoo that the lapping gears 41 and must have the proper ratio of gears The lapping. gears may be considerably wider than the gears to be worn in, in order that axial movement may be imparted, thus .hastening the wearing in and distributing tooth pr1nc1ple,.as for in-- the wear on the lapping gear.

' The principle of operation is more clearly- 45 and 46 respectively toward each other,

in the system. As

will t-ake out all play I summg that normally there is a slight play between the four pairs of teeth, the levers 47 and 43 can be moved outwardly from the line passing through the shafts 49 and 50,

while the shafts 49 and 50 are moved toward each other so that the intercenter distances remain the same. This relative movement can .take place only until the four pairs of teeth are firmly incontact with each other. The relative movement is the same whether the levers 45, and 46 are moved away from each other. A like bell crank system including, however, the teeth 51, 52, 53 and 54 would differ from the one shown only as to the relativity of contact. By moving the levers 47 and 48 toward'each other the ends thereof representing'the teeth would make contact on their oppbsit e sides as compared with the illustration of Fig. 6. This shows ment is that the gear train closes upon itself, i. e. that any power impressedupon one gear is transmitted through all gears of the train and reacts upon the former. All energy expended is thereforemade usefulin the train. The train constitutes its own load and the forces are equally distributed throughout the train, making for uniformity and accuracy.

In the fore oing I have maintained the gears in a fixe intercenter relation by means i of llIlkS interconnectlng the gear shafts or studs. -This arrangement has certain advantages, but within the broader aspect of the invention no links are necessary.

In Figs. 7 and 8, for instance, the studs 61, 62, 63 and 64 may be mounted in a table 60. The holes 65 in which the studs 62, we

and 63 are disposed are preferably slightly lar er than necessary to accommodate the stu s. The studs include each a flange 66 bearing upon one face of the table while a washer may be interposed between the nut 67 and the. otherface of the table. Each shaft, thus may-be clamped in any desired position within the limited range of ad ustment.

. The stud 64 is mounted in a slide 68 which is movable in a slot 69. By means of screws 70 and 71 the slide may be moved in the slot. The portion 64; is preferably eccentric to facilitate angular ad ustment.

The operation is as follows:

The studs 61, 62 and 63 are adjusted on the table and clamped in. desired position, A gauge 7 2 may be applied for facilitating the adjustment. The stud 64 is. clamped to the slide 68 in any desired angular posit on of portion 64, and the slide is moved 1nwardly or outwardly until the hack-lash is the wearin -in eration proceeds, the slide can be fart er a justed to take up the backtaken up. In practice the slide 68 is gradually moved while the gears are in rotation so thats buck tooth in the gear train cannot do any damage. Then progressively as lash caused by the wear.

The forms ofconstruction shown in Figs. 9 and 10 differ from the other forms disclosed by the use of racks for completing the gear train or closing the gear train upon itself. v

In Fig. 9 two gears 73 and 7 4 of different size are in engagement with racks 7 and 76. The two gears are adjustable relatively to each other bymeans of links 77 and screws 78. When the studs or shafts on which the gears are mounted are moved either toward each other or away from each other, the back-lash is taken up to any desired extent. Either rack may be reciprocated, the other, preferably, being held stationary.

In the form shown.in Fig. a single rack- 79 is used to close a gear train upon, itself.

3 The back-lash is eliminated by movement of of links 90 and screws 91.

the gear 80' inwardly toward, or outwardly away from, the rack. The two ears are adjustable relatively to each other y means It is evident that the racks'75 and 76 in 9, and the rack 79 in Fig. 10, are each the equivalent of a term gear is tliere iore intended to nclude I not only all forms of gear mechanism by ear. In the claims the which a train of gears can be closed upon itself, but also racks which are to be considered as gears of infinite radius.

While each form of construction described includes'a gear train closed upon itself, i. e. a gear mechanism in which the transmission may be considered as startin from the teeth of any one member-and lea ing back to the teeth of the same member, I am aware that the invention may be carried out in other in the broader as ect of the invention any construction by w ich a gear may be subjected to a wearing-in action while back-lash 1s prevented is available for the purposes of the invention. I have disclosed varlous arrangements which I consider as particularly well suited solely in order to explain the novel line of action and the new principle in contra-distinction to the methods heretofore used.

I claim:

1. Apparatus for wearing in gears, comrising means for mounting the gears to orm a gear train closed upon itself and meansfor bodily adjusting one of the elements of the gear train relatively to the adjoining gears in mesh with it to eliminate buck-lash in the train.

Q'Apparatus for wearing in gears, comprising means for maintaining a plurality of gears in a substantially fixed angular relationship forming a gear train closed u on itself, means for permitting a slight bodily adjustment of one of the ears relatively to the adjoining gears in mes] with it to eliminate back-lash and means for maintainin said adjustable gear in any desired adjuster position.

3. Apparatus for wearing inogears, .comprising means for mounting the gears to form a gear train closed upon itself and means for permitting relative bodily ad'ustment to change the angular relation 0 the gears and for maintaining constant the intercenter distance between gears which are in mesh with each other.

4. Apparatus for'wearing in gears, comprising a plurality of shafts adapted to support a plurality of gears in the form of a gear train closed upon itself and a link system interconnecting the shafts for permitting each gear to be angularly adjustable relatively to the axis of the adjacent gear in mesh with it and for maintaining the intercenter distance between meshing gears con stant. r

5. The combination of a gear train closed upon itself and a link system interconnecting the gear shafts for permitting relative angular movement of each of two intermeshing gears about the axis of the other and maintaining the intercenter distance between int-ermeshing gears constant.

6. The combination of a gear train closed upon itself and a tog le link system interconnecting the gear siafts.

7. Apparatus for wearing in bevel gears. comprising two shafts mounted in axial supporting the shafts of the intermediate gears for angular movement about the .aligned shafts.

8. Apparatus for wearing in gears, com- 5 prising means for mounting the form a gear train closed upon itsel means for permitting a slight relative adjustment of each pair of adjoining gears, means for ears to' permitting bodily movement of one of the gears symmetrically relatively to its adjoin- 19 ing gears and means for'maintaining the said gear in a definitely adjusted position.

In testimony whereof, I aflix my signature.

WILLIAM E. HOKE. 

